Method of inhibiting opioid tolerance with chimeric hybrid analgesics

ABSTRACT

The present invention provides a method of inhibiting the development of opioid tolerance using novel chimeric hybrid molecules containing an opioid moiety of chemically modified morphine ( 3 ) that binds to and activates the human mu (μ) opioid receptor, with the opioid moiety linked through a novel linker-hinge ( 4 ) to a substance P peptide fragment moiety ( 5 ) that binds to and activates the human substance P receptor. The hybrid alkaloid/peptide analgesics may be administered intrathecally, systemically or orally.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a division of application Ser. No. 10/134,187, filed Apr.26, 2002, as to which Applicant elected a restriction of the inventionas required by an Office Action mailed on Sep. 23, 2003.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.

REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTINGCOMPACT DISK APPENDIX

[0003] A written Sequence Listing and a computer readable form of thesequence listing, consisting of one file namedChimericHybridAnalgesics.ST25.txt on one disk, are attached asAppendices.

BACKGROUND OF THE INVENTION

[0004] 1. Field of the Invention

[0005] The present invention lies firmly within the fields of drug,bio-effective and body treating compositions, more specifically methodsfor acute and chronic pain relief.

[0006] 2. Description of the Prior Art

[0007] The present invention relates to inhibiting the development ofopioid tolerance in the treatment of pain by using novel hybridalkaloid/peptide chimeric molecules. The relief of suffering due to painis an important objective of clinical practice and for restoring qualityto life and the ability to function normally to pain sufferers.

[0008] Pain represents an integrated, complex, perception of noxiousstimuli originating from somatic elements such as arms and legs and/orfrom visceral organs such as heart and liver. Mechanistically, acutepain signaling involves noxious stimulation of free nerve endingsinnervating somatic elements and/or visceral organs leading to theactivation of different types of slowly-conducting afferent fibers ofthe A delta and C classes, terminating in the dorsal sensory spinalcord. A significantly more complex etiology underlies the initiation andpersistence of chronic pain syndromes. This involves initial damage toperipheral nerves innervating somatic and visceral fields, persistentimmunological challenge by cytokines and inflammatory mediators,reorganization of spinal cord and brainstem relay systems, and highercortical adaptation.

[0009] From an established pharmacological perspective, opioids remainthe key agents of choice for treatment of a wide variety of acute andchronic pain states. The prototype opioid analgesic or painkiller ismorphine. Morphine and morphine-related opioids produce theirpainkilling effects by profound pharmacological inhibition of neurons ofthe peripheral/sensory nervous system (PNS) and the central nervoussystem (CNS). The biochemical and cellular effects of morphine,including profound analgesia, are transduced through amembrane-associated G-protein designated the mu (p) opioid receptor(MOR), found in high concentrations within the PNS and CNS.

[0010] Unfortunately, the high degree of pain relief afforded bymorphine and similar opioid compounds is associated with manyundesirable side effects, all mediated through activation of the MOR.They include drowsiness, nausea, emesis (vomiting), changes in mood(dysphoria), respiratory depression, decreased gastrointestinal motility(constipation), pruritis (itching), alterations in endocrine andautonomic function, and physical and psychological dependence leading toaddiction.

[0011] In addition to the adverse physiological sequelae listed above, amajor associated risk is that repeated daily administrations of morphineor morphine-like opioids will eventually induce significant tolerance tothe therapeutic effects of the drug as well as initiating some degree ofphysical dependence. Here opioid tolerance is operationally defined asan escalating dosage regimen required to achieve the same magnitude ofpain relief over a defined time course.

[0012] The administration of escalating dosage so as to achieve the samemagnitude of pain relief can increase the likelihood and the severity ofundesirable side effects such as drowsiness, nausea, emesis (vomiting),changes in mood (dysphoria), respiratory depression, decreasedgastrointestinal motility (constipation), pruritis (itching),alterations in endocrine and autonomic function.

[0013] The degree of tolerance and physical dependence will vary withthe particular opioid employed, the correlation with MOR-selectiveopioids such as morphine being high, the frequency of administration,and the quantity of opioid administered.

[0014] In a wide variety of clinical indications requiring prolonged useof opioids, tolerance induction and addiction are closely linked, withthe development of physical and psychological dependence always a majorconcern. Addiction with physical dependence can be difficult to treatdue to the effects of withdrawal associated with dependence.

[0015] From an established clinical perspective, when morphine and/orsimilar opioid analgesics are administered, the treating health careprovider must recognize that only symptomatic treatment of pain is beingprovided. The health care provider must therefore constantly weigh thebenefits of this immediate (day by day) relief against its costs andrisks to the patient. Accordingly, a decision to relieve the chronicpain in particular clinical situations via administration of currentopioid analgesics may be short sighted and an actual disservice to thepatient.

[0016] Morphine and related MOR-selective opioids also relieve sufferingby ameliorating the emotional or affective component of the painfulexperience. Consequently, if little or no external emotional support isprovided, for example by biofeedback procedures or cognitive behavioraltherapy, some patients may require considerably more than the averagedose of an opioid to experience any relief from pain; similarly, othersmay require more frequent administration. These are major factorssupporting the use of patient-controlled analgesia (PCA) for acutepost-operative pain control, where the affective aspects of painfulexperience are successfully addressed. In effect, many health careproviders frequently tend to prescribe therapeutic dosages of opioidsthat are either too low and/or administered at infrequent time intervalsout of an exaggerated concern for minimizing addiction potential. Theresultant therapeutic regimen fails to provide adequate analgesia overtime.

[0017] In light of the caveats listed above, many health care providersare constantly encouraged to employ measures other than opioid drugs torelieve chronic or acute pain, even when such alternative methods showlimited efficacy in the absence of opioid therapy. These typicallyinclude the use of local nerve block, combinations of antidepressant andanticonvulsant CNS drugs, electrical stimulation, acupuncture, hypnosis,or behavioral modification (Reuler et al., Ann. Intern. Med. 93:588-596(1980)). Additionally, many practitioners respond to their patients'continued complaints of inadequate pain relief with even moreexaggerated concerns about dependency. This is done despite the highprobability that the request for more opioid is only the expectedconsequence of the inadequate dosage originally prescribed.(Sriwatanakul et al., J.A.M.A. 250:926-929 (1983))

[0018] It has also been documented that children are probably more aptto receive inadequate dosages for pain than are adults based on the sametype of reasoning concerning tolerance and dependence Schechter. (N. L.,Curr. Probl. Pediatr. 15 (1985)) Finally, it is useful to remember thatthe typical initial dose of morphine (10 mg/70 kg body weight) relievespost-operative pain satisfactorily in only about two-thirds of patients.(See page 511, Goodman & Gilman, The Pharmacological Basis ofTherapeutics, 7^(th) Ed.)

[0019] Morphine/opioid-induced physiological and psychological sideeffects pose major obstacles to their unfettered, widespread usage asthe mainspring therapeutic regimen for pain relief across clinicalpopulations in the United State and abroad. Intrinsic issues of opioidsafety and efficacy were addressed by a prior invention (U.S. Pat. No.5,891,842), where I established a therapeutic procedure or treatmentregimen for inducing or eliciting a markedly enhanced opioid-dependentanalgesic response within a living subject. That treatment methodologyemploys the concurrent administration of two recognized,self-contradicting and physiologically antagonistic compounds, theopioid analgesic morphine sulfate and the tachykinin peptide substance P(SP), at individual concentrations that had been empirically shown tohave either marginal or completely ineffectual pharmacologicalproperties in vivo. Because noxiously challenged or damaged sensorynerves release a variety of excitatory chemical mediators, including SP,the tachykinin SP had been previously designated as a nociceptive orpain-producing peptide transmitter at the spinal level. Nevertheless, myresearch demonstrates that at prescribed low nanogram concentrations SPappears to be a potent regulator of opioid analgesia in vivo. Despitethis apparent contradiction and the previously demonstratedphysiological antagonism between these compounds in their traditionalformats and conventionally used concentrations, my novel treatmentprocess demonstrated a synergistic relationship over a period of time,and that an effective and efficacious opioid-induced analgesia resultswithin the living subject from the process.

[0020] Unfortunately, because my prior invention requires the concurrentadministration of two different self-contradicting and physiologicallyantagonistic compounds, SP and morphine, it presents difficulties insuccessfully establishing and testing the appropriate concurrent dosagesfor efficacious and safe administration in humans, as reflected by FDAand NIH clinical testing guidelines.

[0021] While morphine is the prototype opioid analgesic or painkiller,its complex alkaloid characteristics differ greatly from those ofpeptides, and SP is a peptide. In subsequent research, therefore,collaborators and I combined the active pharmacological domains of SPand the peptide endomorphin-2 into one chemical entity: a novel sevenamino acid peptide chimera, designated ESP7. Repeated administration ofthe chimeric molecule into the rat spinal cord milieu produced analgesiamediated by the MOR without a loss of potency over a 5-day time course.Essentially, ESP7 represented a non-tolerance forming compound withfuture potential as a specialized spinal analgesic for control of acuteand/or chronic pain. (Foran, et al., A Substance P-opioid chimericpeptide as a unique non-tolerance-forming analgesic, 97 Proceedings ofthe National Academy of Sciences 13 (2000))

[0022] Although ESP7 provided the advantage of a single analgesicmolecule, it has several unfortunate disadvantages. Operationally, thepeptide chemical nature of ESP7 restricts its effective dosage andtime-effect relationship within the CNS due to significant metabolism inthe blood stream. This is supported by collected pharmacological dataindicating significant difficulties encountered by peptide drugcandidates for crossing the mammalian blood-brain barrier (BBB) (EgletonR D, Abbruscato T J, Thomas S A, Davis T P Transport of opioid peptidesinto the central nervous system. J Pharm Sci 1998; 87(11):1433-9), aswell as absorption after oral administration. (Borchardt R, Optimizingoral absorption of peptides using prodrug strategies. J Control Release1999;62(1-2):231-8) Because of this, ESP7 envisioned intrathecaladministration and administration through other means could yield shortduration or no analgesia. Additionally, the peptide endomorphin-2 doesnot have the full analgesic effect of morphine.

[0023] Morphine is a relatively complex organic molecule, termed analkaloid due to its positively charged nitrogen group, unlike theendogenous peptide endomorphin-2 which provided the analgesic moiety inESP7. Morphine is a highly efficacious MOR-selective opioid analgesicand will cross the human BBB, as will its active metabolite morphine6-glucuronide. (Stain-Texier F, Boschi G, Sandouk P, Scherrmann J M,Elevated concentration of morphine 6-beta-D-glucuronide in brainextracellular fluid despite low blood-brain barrier permeability. Br JPharmacol 1999; 128(4):917-24)

[0024] Substance P, however, is a peptide. Chimeric hybrid moleculespossessing an alkaloid moiety and a peptide moiety are unknown to theliterature of analgesia and to clinical practice. Chimeric hybridmolecules possessing an alkaloid moiety to activate the human MOR and apeptide moiety to concurrently activate the human SP receptor (SPR) areunknown to the literature of analgesia and to clinical practice.Chimeric hybrid molecules comprised of one moiety with a chemicallymodified morphine molecule to activate the human MOR and another moietywith a SP fragment to activate the human SPR are unknown to theliterature of analgesia and to clinical practice. The method ofinhibiting the development of opioid tolerance using such chimerichybrid molecules is unknown to the literature of analgesia and toclinical practice.

[0025] Another major challenge is to design a molecule that will crossthe BBB and produce analgesia in a living subject, while inhibitingtolerance development and dependence formation. Such a molecule shouldbe structured in such a way as to activate simultaneously the MOR andSPR domains in the PNS and/or CNS. With respect to both morphine and SP,a variety of alkaloid morphine and SP peptide fragments can besynthesized, having potentially different pharmacological effects ifbound to another moiety. No obvious method is known for the SP moiety tobe cross-linked to a morphine alkaloid moiety in a fashion that theresulting molecule will allow simultaneous activation of both the MORand SPR receptors. Chimeric hybrid molecules with a moiety comprised ofa chemically modified morphine molecule to provide the method totransport active SP fragments across the mammalian blood brain barrierare unknown to the literature of analgesia and to clinical practice.

[0026] Presently there also are no analgesic opioid molecules orchimeras that have been developed that achieve effective analgesia formammalian acute or chronic pain without significant tolerancedevelopment and dependence formation.

[0027] Objects and Advantages. I have invented novel and useful methodsemploying heretofore unknown morphine-SP hybrid chimeras, as I havedescribed below. Several objects and advantages of my present inventionare:

[0028] a. a method for using a molecule that can be dosed to produceeffective analgesia in a living subject, i.e., a mammal (an animal classwhich includes humans), while inhibiting tolerance development;

[0029] b. a method for using a molecule that can be dosed to produceeffective analgesia in a living subject while inhibiting dependenceformation;

[0030] c. a method for using a molecule that can be dosed to produceeffective opioid analgesia and that can be administered through avariety of methods of clinical administration, including oral, systemicand intrathecal administration;

[0031] d. a method for using a molecule that can be dosed to produceeffective opioid analgesia without significant restriction on itseffective dosage and time-effect relationship within the CNS due tometabolism in the blood stream;

[0032] e. a method for using a molecule that can be dosed to yieldeffective opioid analgesia with a reduction in the likelihood ofundesirable side effects;

[0033] f. a method for using a molecule that can be dosed to produceeffective opioid analgesia with a reduction in the likely severity ofundesirable side effects that become manifested by the patient;

[0034] g. a method for using an opioid analgesic that can be dosed foradministration to children without undue tolerance development;

[0035] h. a method for using an opioid analgesic that can be dosed foradministration to children without undue dependence formation; and

[0036] i. a method for using an opioid analgesic suitable for PCA in thetreatment of chronic and/or acute pain.

[0037] Additional objects and advantages of my present invention are:

[0038] a. to provide a method for treating pain with opioid analgesiaand little or no opioid tolerance development;

[0039] b. to provide a method for treating pain with opioid analgesiaand little or no opioid dependence formation;

[0040] c. to provide a method for treating pain with opioid analgesiawith reduced likelihood of undesirable side effects;

[0041] d. to provide a method of opioid analgesia for PCA for acuteand/or chronic pain; and

[0042] e. to provide a method of treating drug abuse by administering asa substitute for the abused drug an analgesic that elicits little or notolerance development or dependency formation and thereafter adjustingthe dosage as tolerance and/or dependence is modulated.

[0043] Still further objects and advantages will become apparent from aconsideration of the following description of my invention.

BRIEF SUMMARY OF THE INVENTION

[0044] The present invention provides a method of inhibiting opioidtolerance using novel chimeric hybrid molecules containing an opioidmoiety of chemically modified morphine that binds to and activates anMOR and a SP peptide fragment moiety that binds to and activates an SPR.

[0045] The present invention utilizes a family of chimeric hybridmolecules in which the alkaloid morphine or its active metabolitemorphine 6-glucuronide are by design carriers of active SP peptidefragments across the mammalian BBB. I have designed thisheretofore-unknown family of hybrid, chimeric molecules with uniquemolecular hinges. This novel family of chimeric hybrid compounds canprovide opioid analgesia in living subjects while inhibiting tolerancedevelopment and dependence formation. These chimeric hybrid compoundscan also be used for drug abuse treatment. The hybrid alkaloid/peptideanalgesics may be administered systemically, intrathecally or morepreferably, orally.

[0046] In one embodiment, the independent functional domains consistingof chemically modified morphine and a SP fragment are covalently crosslinked through the four carbon organic molecule succinic acid. Inanother embodiment, the independent functional domains consisting ofchemically modified morphine and a SP fragment are covalently crosslinked through the four carbon organic molecule gamma-hydroxy butyricacid. In another embodiment, the independent functional domainsconsisting of chemically modified morphine and a SP fragment arecovalently cross linked through the six carbon carbohydrate d-glucuronicacid. The use of three such molecules, succinic acid, gamma-hydroxybutyric acid, and d-glucuronic acid, as molecular hinges to cross linktwo active pharmacological domains of disparate chemical nature, i.e., amulti-ringed opioid alkaloid structure and a linear peptide structure,is not intuitively obvious or predictable from the prior art. The use ofsuccinic acid, gamma-hydroxy butyric acid, and d-glucuronic acid, asmolecular hinges to cross link a pharmacologically active peptide to apharmacologically active opioid is novel and unknown to the literatureof analgesia and to clinical practice.

[0047] The chimeric hybrid molecule may be designed to have a pluralityof SP moieties consisting of pharmacologically active COOH-terminalfragments of SP and a plurality of opioid alkaloid moieties consistingof morphine chemically modified at its 6′hydroxyl group. The pluralityof opioid moieties are each designed to bind to and activate an MOR. Theplurality of SP fragments are each designed to bind to and activate anSPR. Because the MOR- and SPR-activating domains are of chemicallydifferent compositions, i.e., a multi-ringed alkaloid structure and alinear peptide structure, respectively, it is not intuitively obviousthat they may be combined in a functionally active molecule. This isachieved, however, by incorporating a novel molecular hinge regionconsisting of succinic acid, or gamma-hydroxy butyric acid, ord-glucuronic acid. The existence of functionally active chimeric hybridmolecules, of internally differing chemical nature, combining MOR- andSPR-activating domains linked by a novel molecular hinge are unknown tothe literature of analgesia and to clinical practice.

[0048] The invention provides a method for inhibiting the development ofopioid tolerance using pharmaceutical compositions including hybridalkaloid chimeric molecules and a pharmaceutically acceptable carrieruseful for the treatment of pain. It represents methods of treating painusing novel hybrid alkaloid/peptide chimeric molecules containing anopioid and SP moiety designed to achieve coincident activation ofpopulations of MORs and SPRs as a novel pain treatment without toleranceand dependence. The hybrid alkaloid/peptide analgesics may beadministered systemically or more preferably, orally. Solubility,absorption, and penetration through the human BBB will be markedlyenhanced due to the hydrophilic properties of morphine. The inventiontherefore provides novel methods for treating pain using chemicallymodified morphine to serve both as an opioid analgesic as well as apharmaceutically acceptable carrier for SP peptide absorption andstability after systemic administration as well as penetration throughthe human BBB. In these novel attributes, the method of inhibitingopioid tolerance development using hybrid alkaloid chimeric moleculesdiffers substantially from prior art including the use of peptide ESP7.

[0049] The method of inhibiting the development of opioid toleranceusing novel hybrid alkaloid chimeric molecules encompassing threechemically disparate functional domains, i.e., a ringed alkaloidMOR-activation domain, a peptide SPR-activation domain, and a flexibleorganic acid hinge domain, is unknown to the preclinical and clinicalliterature of pain and analgesia.

[0050] A desired objective of the present invention is that the hybridalkaloid/peptide chimeric molecules can be administered to produceclinically efficacious opioid analgesia with little or no development ofopioid tolerance. With little or no tolerance development, escalatingdosages will not be required to achieve the same pain killing effect andopioid dependence formation and undesirable side effects associated withescalating opioid dosages will be avoided or markedly reduced.

[0051] Detailed descriptions of one or more embodiments of the inventionare described below. The novelty of the invention, as amply describedabove, will be apparent from the detailed description of structure andsynthesis and from the claims. In the specification and the appendedclaims, the singular forms include plural referents unless the contextclearly dictates otherwise. All technical and scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which this invention belongs. Unless expresslystated otherwise, the techniques employed or contemplated herein arestandard methodologies well known to one of ordinary skill in the art.The examples of embodiments are for illustration purposes only. Allpatents and publications cited in this specification are incorporatedherein by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

[0052]FIG. 1 illustrates two domains of the morphine nucleus, one beinga conjugation domain useable to synthesize the chimeric hybrid compoundsand the other being the active domain that activates the MOR.

[0053]FIG. 2 illustrates schematically how a chimeric hybrid molecule isconstructed of three, linked components, i.e., a morphine nucleus, alinker-hinge and an SP fragment.

DETAILED DESCRIPTION OF THE INVENTION

[0054] Description—FIGS. 1 and 2. The present invention provides amethod of inhibiting the development of opioid tolerance using hybridalkaloid chimeric molecules having an MOR binding and activation moietyand an SPR binding and activation moiety. The hybrid alkaloid chimericmolecules are designed to bind to and activate populations of MORs andSPRs located primarily within the human CNS, but also in the human PNS,involved in pain mediation and analgesic responses. While the alkaloidmorphine and the peptide SP frequently exhibit slight cross reactivityto other opioid and tachykinin receptor types, respectively, they aregenerally characterized, as exhaustively detailed in the literature, bya very high degree of affinity for the MOR and SPR, respectively. Thepreservation of independent binding and activation moieties in onehybrid alkaloid/peptide molecule containing a multi-ringed alkaloidstructure and a linear peptide structure, is not described in the priorart and distinguishes the present invention as novel and not evolvingfrom prior invention.

[0055] The existence of functionally active chimeric hybrid molecules,of internally differing chemical nature, combining MOR- andSPR-activating domains linked by a novel molecular hinge are unknown tothe literature of analgesia and to clinical practice. Because the MOR-and SPR-activating domains are of chemically different compositions,i.e., a multi-ringed alkaloid structure and a linear peptide structure,respectively, it is not intuitively obvious that they may be combined ina functionally active molecule.

[0056] I have achieved this by design and incorporation of a novelchemical linker-hinge region consisting of succinic acid, orgamma-hydroxy butyric acid, or d-glucuronic acid, to connect within asingle molecule an alkaloid MOR-activation domain and a peptideSPR-activation domain that are modified to be compatible with thathinge. The design of novel hybrid alkaloid chimeric moleculesencompassing three chemically disparate functional domains, i.e., aringed alkaloid MOR-activation domain, a peptide SPR-activation domain,and a flexible organic acid hinge domain, is unknown to the preclinicaland clinical literature of pain and analgesia. The use of such hybridalkaloid chimeric molecules to inhibit the development of opioidtolerance is unknown to the preclinical literature and clinicalliterature of pain and analgesia.

[0057] The chimeric multi-ringed alkaloid structure of morphine linkedto the linear peptide structure of SP is illustrated in FIG. 1 and FIG.2. FIG. 1 illustrates that a morphine nucleus can be considered asdivided into two domains, one of which is a conjugation domain 2 useableto synthesize the chimeric hybrid compounds from the 6′OH position onthe morphine nucleus and the other of which is an active domain 1 thatactivates the MOR. FIG. 2 illustrates schematically how a chimerichybrid molecule is constructed of three interlocking components, thealkaloid morphine nucleus 3, a chemical-linker hinge 4, and a peptide SPfragment 5. The chemical linker-hinge 4 links to the alkaloid morphinenucleus 3 at its 6′OH position. The chemical linker-hinge 4 also linksto the peptide SP fragment 5. The linker-hinge allows the N-terminalopioid receptor binding moiety or active domain of the morphine nucleusfragment of the hybrid chimeric molecule be able to activate an MOR andthe C-terminal SP receptor agonist binding moiety of the SP fragment tobe able to activate an SPR.

[0058] The method employs chimeric hybrid molecules that may be designedto have a plurality of SP moieties consisting of pharmacologicallyactive COOH-terminal fragments of SP and a plurality of opioid alkaloidmoieties consisting of morphine chemically modified at its 6′hydroxylgroup. The plurality of opioid moieties are each designed to bind to andactivate an MOR. The plurality of SP fragments are each designed to bindto and activate an SPR.

[0059] I refer to the following amino acid sequences using the Seq. Id.Nos. below: SEQ. ID. NO. SEQUENCE 1 Lys Pro Gln Gln Phe Phe Gly Leu Met2 Gln Gln Phe Phe Gly Leu Met 3 Phe Phe Gly Leu Met

[0060] Nine preferred embodiments of chimeric hybrid analgesics whichthe method of the present invention can employ are listed in table 1TABLE 1 Embo- μ diment receptor # agonist Hinge SP receptor agonistSequence 1 Mor- D- N- SEQ. ID. phine Glucuronic Acetylsubstance P [3-NO. 1 Acid 11]: Ac-KPQQFFGGLM- NH2 2 Mor- D- Substance P [5-11]: SEQ.ID. phine Glucuronic QQFFGLM-NH2 NO. 2 Acid 3 Mor- D- Substance P[7-11]: SEQ. ID. phine Glucuronic FFGLM-NH2 NO. 3 Acid 4 Mor- SuccinicN- SEQ. ID. phine acid Acetylsubstance P [3- NO. 1 11]: Ac-KPQQFFGLM-NH2 5 Mor- Succinic Substance P [5-11]: SEQ. ID. phine acid QQFFGLM-NH2NO. 2 6 Mor- Succinic Substance P [7-11]: SEQ. ID. phine acid FFGLM-NH2NO. 3 7 Mor- Gamma-OH N- SEQ. ID. phine Butyric Acetylsubstance P [3-NO. 1 Acid 11]: Ac-KPQQFFGLM- NH2 8 Mor- Gamma-OH Substance P [5-11]:SEQ. ID. phine Butyric QQFFGLM-NH2 NO. 2 Acid 9 Mor- Gamma-OH SubstanceP [7-11]: SEQ. ID. phine Butyric FFGLM-NH2 NO. 3 Acid

ADVANTAGES OF THE PRESENT INVENTION

[0061] The advantages of morphine as an analgesic that can cross the BBBare well known to the literature. The advantages of simultaneousactivation of an MOR and SPR to modulate the activation of the MOR andto reduce or eliminate tolerance development and dependence formationare also known from the literature, such as a prior invention of mine(U.S. Pat. No. 5,891,842) and the work of colleagues of mine and Iidentified above relating to ESP7.

[0062] From the description above, a number of advantages of my methodof inhibiting opioid tolerance development using chimeric hybridanalgesic molecules becomes evident:

[0063] a. the method will inhibit tolerance development while beingdosed to provide morphine opioid analgesia;

[0064] b. the method will inhibit dependence formation while being dosedto provide morphine opioid analgesia;

[0065] c. the method can be used by means of administration of themolecules through a variety of methods of clinical administration, inaddition to intrathecal administration;

[0066] d. the method will not have the significant dosage andtime-effect restrictions of peptides due to metabolism in the bloodstream;

[0067] e. because of the modulation of an MOR by SPR activation, anescalating dosage typical of morphine is not required;

[0068] f. because the escalating dosage typical of morphine is notrequired, the likelihood and severity of undesirable effects associatedwith escalating morphine dosage will be reduced; and

[0069] f. the method can be used to administer a chimeric hybridanalgesic molecule as a substitute for an abused opioid drug and,because the molecule elicits little or no tolerance development ordependency formation, its dosage can thereafter be adjusted as toleranceand/or dependence is modulated.

[0070] Further advantages will become apparent to those skilled in theart.

[0071] Making My Invention. The present invention can be made by aperson skilled in the art, as follows. The method uses chimeric hybridanalgesic molecules to inhibit the development of opioid tolerance. Theseparate MOR- and SPR-activating moieties are synthesized and purifiedor isolated from natural sources and then chemically cross-linked toform hybrid alkaloid/peptides chimeric molecules. All syntheses utilizewell-established standard organic chemistry techniques and reagents. SPpeptide fragment moieties are synthesized prior to covalent attachmentto the morphine nucleus (FIG. 1). For these purposes, a variety ofpeptide synthesis methods are common in the art, including synthesisusing an automated peptide synthesizer and employing Fmoc amino acids.(Merrifield, Science 232: 241-247 (1986); Barany, et al, Intl. J PeptideProtein Res. 30: 705-739 (1987); Kent, Ann. Rev. Biochem. 57:957-989(1988), and Kaiser, et al, Science 243: 187-198 (1989)) SP peptidefragments are purified to over 99% chemical purity using standardpeptide purification techniques such as reverse-phase high-pressureliquid chromatography (HPLC). The chemical structures of SP peptidefragments, purified by HPLC, are confirmed by mass spectroscopicanalysis.

[0072] Morphine is chemically modified by covalent attachment at its6′OH group to the hinge-forming organic molecules described above:d-glucuronic acid, succinic acid, gamma-hydroxy butyric acid. Chemicallymodified morphine derivatives, i.e., morphine-6-glucuronide,morphine-6-hemi-succinate, morphine-6-gamma-hydroxy butyrate, arecovalently attached to SP peptide fragments using standard condensingagents such as water soluble carbodiimide (CDI).

[0073] Alternatively, SP peptide fragments are chemically modified bycovalent attachment at their free amino groups to the hinge-formingorganic molecules described above: d-glucuronic acid, succinic acid,gamma-hydroxy butyric acid. Chemically modified SP peptide fragments,i.e., SP fragment-glucuronide, SP fragment-hemi-succinate, SPfragment-gamma-hydroxy butyrate, are covalently attached to morphineusing standard condensing agents such as water soluble CDI.

[0074] Prior to pharmacological testing, the novel chimeric hybridalkaloid/peptide molecules comprising a cyclic alkaloid MOR-activatingmoiety and an SPR-activating peptide moiety (such as those in Table 1)are purified to over 99% purity by standard chromatographic techniquessuch as reverse-phase HPLC. This represents less than about 1% chemicalprecursors or non-peptide chemicals in the final preparations. Thechemical structures of chimeric hybrid alkaloid/peptide molecules areconfirmed by mass spectroscopic analysis. The chimeric hybrid moleculesare then subjected to standard pharmacological testing.

[0075] Preclinically, a well-established method is used to assess theanalgesic properties of the novel chimeric hybrid compounds, that beingthe tail flick test, which is administered to rats following parenteralor CNS administration. Additional tests of analgesic responsivenessinclude the paw withdrawal and hotplate tests, i.e., methodswell-established as common in the art. Preclinical testing of analgesiaand tolerance development is conducted by administration of the chimerichybrid compounds over time and alternatively using opioid and SPblockers in well-established analgesic testing methods. Furtherpreclinical and clinical testing is conducted in conformity withgovernmental drug regulations.

[0076] Having made the chimeric hybrid molecules, they are administeredto inhibit the development of opioid tolerance through means of clinicaladministration of analgesia well known to persons skilled in the art.

[0077] Using My Invention. The present invention further providesmethods of treating a mammal for relief of pain by administering apharmaceutical composition (as described above) in order to produceanalgesia in the subject/patient. The invention is used by personsskilled in the art, as follows: Pharmaceutical compositions of theinvention are formulated to be compatible with their intended routes ofadministration, e.g., parenteral, intrademal, subcutaneous, injectable,intravenous, oral, intradermal, subcutaneous, transdermal (topical),transmucosal, and rectal administration.

[0078] Solutions or suspensions suitable for parenteral, intradermal, orsubcutaneous application can include the following components: a sterilediluent such as water for injection, saline solution, fixed oils,polyethylene glycols, glycerine, propylene glycol or other syntheticsolvents; antibacterial agents such as benzyl alcohol or methylparabens; antioxidants such as ascorbic acid or sodium bisulfite;chelating agents such as ethylenediaminetetraacetic acid; buffers suchas acetates, citrates or phosphates. The parenteral preparation can beenclosed in ampoules, disposable syringes or multiple dose vials made ofglass or plastic.

[0079] Pharmaceutical compositions suitable for injectable use includesterile aqueous solutions or dispersions and sterile powders for theextemporaneous preparation of sterile injectable solutions ordispersion. For intravenous administration, suitable carriers includephysiological saline, sterile or bacteriostatic water, or phosphatebuffered saline (PBS). In all cases, the compositions must be sterileand should be fluid to the extent that they are easily injectable bysyringe. Proper fluidity may be maintained by the use of a coating suchas lecithin, by the maintenance of the required particle size in thecase of dispersion and by the use of surfactants. Preservation ofchemical and pharmaceutical integrity is achieved by variousantibacterial and antifungal agents: e.g., parabens, chlorobutanol,phenol, ascorbic acid, thimerosal, etc. In many cases, it will bepreferable to include isotonic agents, for example, sugars, polyalcoholssuch as manitol, sorbitol, sodium chloride in the composition. Prolongedabsorption of the injectable compositions can be brought about byincluding in the composition an agent which delays absorption, forexample, aluminum monostearate and gelatin.

[0080] Sterile injectable solutions can be prepared by incorporating theactive compound (e.g., chimeric hybrid molecules) in the required dosagein an appropriate solvent with one or a combination of ingredientsenumerated above, as required, followed by filtered sterilization.

[0081] Oral compositions generally include an inert diluent or an ediblecarrier. They can be enclosed in gelatin capsules or compressed intotablets. For the purpose of oral therapeutic administration, the activecompound can be incorporated with binders and used in the form oftablets, troches, or capsules. Pharmaceutical binding agents, and/oradjuvant material can be included as part of the composition. Thetablets, pills, capsules, troches and the like can contain any of thefollowing ingredients, or compounds of a similar nature: a binder suchas microcrystalline cellulose, gum tragacanth or gelatin; an excipientsuch as starch or lactose, a disintegrating agent such as alginic acid,Primogel, or corn starch; a lubricant such as magnesium stearate orSterotes; a glidant such as colloidal silicon dioxide.

[0082] Suitable intradermal, subcutaneous, transdermal (topical), andtransmucosal formulations include: gels, creams, solutions, emulsions,suspensions, carbohydrate polymers, biodegradable matrices thereof,vapors, mists, aerosols and other inhalants, and skin patches. Rectalformulations also include suppositories and enemas.

[0083] Examples of suitable pharmaceutical carriers for the variousforms of administration include any of the standard pharmaceuticallyaccepted carriers known to those of ordinary skill in the art. Examplesof pharmaceutical carriers include but are not limited to bufferedsaline solution, water, emulsions, various wetting agents, tablets,coated tablets and capsules. Besides an effective amount of thecompounds described in the present invention, pharmaceuticalcompositions may include suitable diluents, preservatives, solubilizers,emulsifiers, adjuvant and/or carriers. Examples of optional ingredientswhich may be included in the pharmaceutical compositions of the presentinvention include antioxidants; low molecular weight polypeptides;proteins such as serum albumin, gelatin or immunoglobulins; amino acidssuch as glycine; chelating agents; sugar alcohols.

[0084] Because of the modulation of opioid tolerance and dependence, theinvention may also be used for drug abuse intervention throughadministration of one or more embodiments of the chimeric hybridanalgesics which are the subjects of the invention in substitution forthe drug to which the patient became tolerant and/or on which thepatient became dependent.

[0085] Conclusions, Ramifications and Scope. The reader thus will seethat my invention provides a novel and useful method for inhibiting thedevelopment of opioid tolerance using novel chimeric hybrid moleculescontaining an opioid moiety of chemically modified morphine that bindsto and activates the MOR and a SP peptide fragment moiety that binds toand activates the SPR, to produce opioid analgesia in a living subjectwith little or no tolerance development and dependence formation.

[0086] While my description contains many specifications, these shouldnot be construed as limitations on the scope of my invention, but ratheras an exemplification of one or more of the preferred embodiments of myinvention. Other variations are possible. Accordingly, the scope of myinvention should be determined by the appended claims and their legalequivalents and not by the embodiments illustrated in the foregoingdescription.

1 3 1 9 PRT mammalian 1 Lys Pro Gln Gln Phe Phe Gly Leu Met 1 5 2 7 PRTmammalian 2 Gln Gln Phe Phe Gly Leu Met 1 5 3 5 PRT mammalian 3 Phe PheGly Leu Met 1 5

I claim:
 1. A method of inhibiting the development of opioid toleranceby clinically administering a chemically combination of apharmacologically active form of substance p with morphine in a chimerichybrid molecule wherein morphine, chemically modified and covalentlylinked through its 6′OH group, comprises a cyclic alkaloid moiety whichbinds as an agonist to a mammalian or human (μ) opioid receptor; andwherein a pharmacologically active C-mu terminal substance P fragment,chemically modified and covalently linked through its free NH2 group,comprises a peptide moiety which binds as an agonist to amammalian/human substance p receptor; and wherein a compact, butflexible, molecular hinge covalently cross links morphine through its6′OH group to the free NH2 group of the substance p receptor agonistmoiety, so as to allow both the mu (μ) opioid receptor and the substancep receptor agonist moieties to activate their respective receptorssimultaneously and independently.